TRANSITION TO ANAER0BI0SI8 143 



at all. This condition is aggravated by the fact that no 

 circulatory system is present that would distribute the 

 oxygen to the tissues. The inner layers must therefore 

 have an oxygen tension of zero or nearly zero and their 

 cells obviously must gain their energy more or less com- 

 pletely through anaerobic processes (Krogh, /. c). If 

 the oxygen tension in the surroundings is increased or 

 decreased, a thicker or thinner layer of tissues, respec- 

 tively, will receive an adequate oxygen supply and, as a 

 consequence, the over-all oxygen consumption will rise or 

 fall. 



If the assumption is correct that the rate at which 

 oxygen diifuses into the tissues is the limiting factor in 

 the oxygen consumption, it should obviously be possible 

 to eliminate or at least reduce the influence of the oxy- 

 gen tension by reducing the distance through which the 

 gas has to diffuse in order to reach the cells where it is 

 used. Experiments of that type were undertaken by 

 Harnisch (1932). He determined the oxygen consumption 

 of sections of tissues from the body wall of actinians in 

 presence of varying percentages of oxygen, and also of 

 pieces of tissues that had been either simply minced with 

 scissors or minced and then forced through silk gauze. 

 His results, given in relative values only, are summa- 

 rized in Table 19. It is obvious that in whole sections the 

 oxygen consumption changed with the tension through- 

 out the entire range, as was found by Henze (1910) for 

 Avhole animals. The pieces forced through silk gauze, on 

 the other hand, exhibited a fairly uniform aerobic res- 

 piration at least at tensions extending from 11 to 60 

 per cent oxygen. However, the enormous increase in 

 oxygen consumption in pure oxygen seems to indicate 

 that other factors than mere diffusion are also involved. 

 Except for this one point, the experiments of Harnisch, 

 as a whole, lend support to the explanation proposed by 

 Henze and Krogh. 



